Flow rate regulator to reduce variation in temperature of water drawn from a mixing device

ABSTRACT

A new use of a flow rate regulating device ( 5, 6 ) is disclosed whose feature consists of the fact that, when inserted in a water pipeline, it permits the passage of a flow of water having a substantially constant flow rate and predetermined in keeping with the variation within certain limits of the pressure at which the water is supplied to the device, thus constituting a variable resistance that is opposed to the water flow. The new use is especially designed to perform the function of reducing the temperature peak presented by the mixed water drawn from a thermostatic mixing device ( 1 ) during the transitory period of regulation when the pressure of the water supplied to one of the inlets ( 2, 3 ) of the thermostatic mixing device ( 1 ) varies abruptly with respect to the pressure of the water supplied to the other inlet of the thermostatic mixing device ( 1 ). The new use consists of the insertion of the flow rate regulating device ( 5, 6 ) in the passage of at least one of the flows of supply of cold water and hot water (inlets  2, 3 ) directed to the thermostatic mixing device ( 1 ). The flow rate regulator ( 5, 6 ) can be inserted on the passage of both supply flows of cold and hot water, of the hot water supply flow only, or, and preferably, of the cold water supply flow only.

TECHNICAL FIELD

The present invention relates to a hydraulic installation whichcomprises a mixing device having an inlet connection for receiving aflow of supply of cold water, an inlet connection for receiving a flowof supply of hot water, and a delivery connection for delivering mixedwater. In particular, this invention relates to a new use of a knowndevice called “flow rate regulator” in connection with a mixing deviceto perform a function different from the functions for which this knowndevice has been employed so far.

BACKGROUND OF THE DISCLOSURE

“Flow rate regulators” are currently commercially available and areknown, for example, in a simple form from catalog 133/16/99 of theDieter Wildfang GmbH of Müllheim (Germany), and in a form combined witha nonreturn valve from German Patent No. 196 03 393. The basic featureof this device consists in the fact that, when inserted in a waterpipeline, it permits a flow of water with a substantially constant flowrate that is preset upon the variation—within certain although widelimits, for example, from 1 to 10 bar—of the pressure at which the wateris supplied to the device. This device, therefore, represents a variableresistance to the flow, in other words, it opposes a resistance to theflow which, starting with a certain value of a given supply pressure,keeps diminishing strongly with the decrease of the water supplypressure. The substantially constant flow rate, which the flow rateregulator allows to pass, depends on the design features of the device.

The flow rate regulator is currently employed, in particular:

in order to make sufficiently constant the flow that runs through aninstantaneously boiler, which would not work regularly if the flowrunning through it were not comprised between certain limits;

to limit the flow rate drawn from a shower, as prescribed in certainregulations; and

to limit the flow rate drawn from a faucet for the purpose of savingwater.

The phenomenon with respect to which the invention proposes theemployment of a flow rate regulator, in particular, involves thephenomenon of the temperature peak presented by the thermostatic mixingdevices when there is a noteworthy and abrupt variation in the watersupply pressure to one of the hot-and-cold water increments, a variationwhich, in most cases, involves an abrupt reduction of the cold waterpressure because, from the water supply network, there is drawn a strongflow rate by an apparatus that entails high absorption such as aflowmeter flushing water device. The development of the phenomenoninvolved will be described with reference to this most frequent case.

When the pressure of the cold water supplied to a thermostatic mixingdevice diminishes abruptly, while the hot water supply pressure remainsconstant or almost constant, then the incoming cold water flow willdiminish correspondingly, and, therefore, the temperature of the mixedwater goes up abruptly. The temperature of the mixed water is detectedby a thermometric element which, in the presence of a temperatureincrease, activates a regulating mechanism that provides for choking apassage for the hot water so as to return to the correct value imposedby the temperature of the mixed water. However, this regulating actioninvolves a certain hysteresis due to the fact that regulation requires acertain period of time to be performed. During the period of transitionin which takes place the regulating action as such, the temperature ofthe mixed water that is drawn presents an initial peak indicating atemperature rise, which can involve several degrees and which is thengradually attenuated until the prescribed temperature is once againreached. This temperature rise peak is extremely disturbing to the user,for example, during a shower, and it attains particularly high values,which can even turn out to be dangerous.

The same phenomenon could happen if, in a somewhat special case, therewere to be an abrupt increase in the hot water supply pressure. Instead,a similar phenomenon, but with a temperature peak decline, occurs whenit is the hot water supply pressure that drops abruptly or when the coldwater supply pressure rises abruptly.

Similar phenomena not in the form of temperature peaks but in the formof variations in the temperature of the water that is drawn occur undersimilar conditions even in nonthermostatic mixing devices.

The inconveniences connected with this phenomenon can be partly remediedby installing in water supply pipelines up the line from thethermostatic mixing device a pressure compensator. However, thisexpensive additional device increases the size and complexity of theinstallation also because it must be connected to both of the cold waterand hot water supply pipelines; that raises the cost of the equipmentand of the operations involved in its installation; besides, this is adelicate operation; it is easily subject to failure, especially due todeposits, and it requires a certain amount of maintenance. By the way,it does not operate in an entirely satisfactory manner because, when thepressure is reduced in a pipeline, the compensator provides for thereduction of the passage offered to the other pipeline and thus correctsthe mixing ratio but modifies the flow rate that is drawn. On the otherhand, the operation of the pressure compensator can under certainconditions cause phenomena of instability.

As a matter of fact, the phenomenon described here is considerably toneddown because, without using a pressure compensator proposed, forexample, in Italian Patent Application No. TO 99 A 000 162, it involvesintroducing into one or both water supply connections of thethermostatic mixing device and particularly in the connection for thesupply of cold water a choking member. This choking member has theeffect of causing the regulating mechanism controlled by thethermometric element to be arranged normally in an asymmetrical positionand, in particular, if the choking member is inserted in the cold watersupply connection, it is arranged closer to the position in which theregulating mechanism actually chokes the passage of the hot water.Consequently, the regulating mechanism itself is more ready to react toa rise in the temperature of the mixed water and it is therefore capableof causing a more moderate temperature peak.

Further, document GB-A-2 303 685 discloses a mixer control comprising amixing chamber at which thermostatically controlled valve means isprovided for controlling mixture of hot and cold water for an adjustabledischarged water temperature selectable by manual operation of the valvemeans, an outlet by way of which mixed water from the mixing chamberpasses to be discharged from the mixer control, and a temperatureresponsive shut-off valve at the outlet which is normally open but whichis operated automatically to close the outlet when the temperature ofwater from the mixing chamber exceeds a predetermined value which willnormally be at or just above the maximum permitted operating temperatureof the mixer control.

Although the shut-off valve according to this prior art provides aback-up for the thermostatically controlled valve means to cut-off waterdischarge should the valve means not respond, or not respond quicklyenough, to an increase in the discharged water temperature to anundesirable level, a disadvantage of this prior art consists in the factthat the shut-off valve considerably adds to the structural complexityand cost of the known mixer control.

In addition, document GB-A-2 303 685 generally discloses that “flowregulators” may be included at the hot and cold inlets to optimiseperformance of the mixer control in high or uneven inlet water pressureconditions. The structure and the function of these “flow regulators”however are not described in more detail.

The object of the present invention is to provide a hydraulicinstallation in which undesirable temperature increases as describedabove are reduced or eliminated at low effort and cost.

SUMMARY OF THE DISCLOSURE

According to the present invention a hydraulic installation is providedwhich comprises a mixing device having an inlet connection for receivinga flow of supply of cold water, an inlet connection for receiving a flowof supply of hot water, and a delivery connection for delivering mixedwater, and which further comprises a flow rate regulating deviceinserted in the passage of at least one of the flows of supply of coldwater and hot water directed to the mixing device, wherein the flow rateregulating device is adapted to permit, within certain limits of thepressure at which the water is supplied to the flow rate regulatingdevice, the passage of a flow of water having a predetermined andsubstantially constant flow rates, thus reducing the temperature pealpresented by the mixed water drawn from the mixing device when thepressure of the water supplied to one of the inlet connections variesabruptly with respect to the pressure of the water supplied to the otherinlet connection.

Research conducted by the inventor showed that extremely moresatisfactory results are obtained if, in place of a standard chokingmember as disclosed in Italian Patent Application No. TO 99 A 000 162,constituting a resistance with an unchangeable value, one installs aflow rate regulating device at least in one water supply connection andpreferably in the water supply connection for the cold water or possiblyin both water supply connections.

The reason for the significant improvement in the performance of thethermostatic mixing device resides in the fact that, when the pressurein a water supply connection in which is installed a flow rate regulatordrops abruptly, the resistance opposed to the flow of the flow rateregulator also drops immediately and, therefore, the initial variationof the temperature of the mixed water, which gives rise to theregulating action of the thermometric element, is for this reason alonemuch more reduced than what would be the case if the flow rate regulatorwere not installed. On the other hand, the flow rate regulator by itselfconstitutes a choking member and therefore offers the above-mentionedadvantage of speeding up the regulating action when compared to what itwould be if such a choking member were not there. The coexistence andthe synergism of these two actions give rise to significant constantadvantages. An important factor in this action is represented by thefact that the reaction of the flow rate regulator is extremely fast andpractically instantaneous. It follows from this that a thermostaticmixing device which, in the absence of the proposed provision, wouldhave given rise to a temperature rise peak of several degrees, insteadleads to a significantly reduced temperature peak, for example,amounting to ½ a degree, which does not cause any inconvenience and mayeven pass unnoticed.

Naturally, the flow rate regulator installed in at least one watersupply connection of the thermostatic mixing device can be of the typecombined with a nonreturn value in all cases where the presence of sucha valve is desirable.

These and other features, purposes and advantages of the object of thisinvention will appear more clearly in the following description of anembodiment, consisting in a nonrestrictive example with reference to theenclosed drawing.

BRIEF DESCRIPTION OF THE DRAWING

Reference now is made to the accompanying drawing in which FIG. 1illustrates a thermostatic mixing device in which one uses at least oneflow rate regulator for the above-described functions.

FIGS. 2 and 3 are variations of the thermostatic mixing device shown inFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 presents an outside view of an example of the thermostatic mixingdevice comprising a body 1 with two inlet connections 2 and 3 and with adelivery connection 4. The internal structure of the thermostatic mixingdevice is not shown because it can be of any kind and is not involved inthe application of the invention. Inlet connections 2 and 3 are shown ina partial cross-section to demonstrate how a flow rate regulator wouldbe inserted by way of implementation of the invention.

With reference to connection 2, which is assumed to be the inletconnection for the cold water, it will be noted that there is insertedin it a flow rate regulator 5 of the simple type, devoid of any partsthat work as nonreturn valve. It can be employed in all cases where itis not required to prevent an inverted flow as well as in cases wheresuch prevention is required but is entrusted to separate means.

The performance of the thermostatic mixing device thus equipped is aswas described in the introduction. The presence of a resistance to theentry of cold water, represented by the flow rate regulator, causes theregulating mechanism of the thermostatic mixing device (of whatever kindit may be) to be arranged normally in the asymmetrical position, closerto the position that reduces the intake of hot water than to theposition that reduces the intake of cold water so that the thermostaticmixing device will react more rapidly to a trend toward an increase inthe temperature of the water that is drawn rather than to a tendencytoward a diminution of said temperature. On the other hand, in casethere is a variation in the water supply pressure in the connection inwhich it is installed, the flow rate regulator modifies the resistanceto the flow so as to bring about a great reduction in the influencederiving from the variation of the pressure upon the temperature of themixed water. The combination of these two actions gives rise to thesignificant effect of minimizing the temperature peak, which was foundas a result of this provision.

Flow rate regulator 5 is shown as installed directly in inlet connection2 of the thermostatic mixing device because the latter is theinstallation that ensures the minimum size and because it is in manycases preferably, but naturally, the flow rate regulator could also beinstalled in an accessory to be applied between a water supply pipe andthe intake connection of the thermostatic mixing device, or it could beinstalled in the water supply piping itself.

If there is a requirement for preventing an inverted flow, as was statedearlier, in place of a simple flow rate regulator, one can then installa flow rate regulator connected to a nonreturn means. This installationis represented in relation to the inlet connection 3 or the thermostaticmixing device in which is installed a flow rate regulator 6 which, interms of design, is linked to a nonreturn means 7.

It is obvious that it may be sufficient and in many cases it may bepreferable that a single flow rate regulator be installed in only oneintake connection of the thermostatic mixing device and especially inthe intake connection for the cold water. However, in other cases, itmay preferable that both the intake connections of the thermostaticmixing device be equipped with a flow rate regulator and, in this case,both of them can be simple, both can be provided with nonreturn meansor, as in the example shown, one of them can be simple and the other onecan be provided with nonreturn means.

In case each of the intake connections of a thermostatic mixing deviceis provided with a flow rate regulator, it is particularly advantageousto employ two flow rate regulators, so arranged as to draw differentflow rates and precisely to insert in the cold water inlet connection aflow rate regulator that is so arranged as to draw a flow rate that isless than the flow rate for whose delivery is arranged the flow rateregulator inserted in the hot water inlet connection. In this way, thegreater resistance to the flow, created by the flow rate regulatorinserted in the cold water inlet connection, conserves and enhances theadvantageous effects in terms of giving rise to an asymmetrical positionof the control mechanism that is activated by the thermometric element.

As will be noted, the known uses of a flow rate regulator do not in anyway suggest the application of such a device to the inlet of athermostatic mixing device nor would they hint at the supposition thatsaid application could lead to a significant reduction of thetemperature peak that is observed during the regulation transitionperiod subsequent to an abrupt variation in the water supply pressure.

The use of a flow rate regulator, incorporated in an automatic valveintended for the different function of stabilizing the operation of athermostatic mixing device, was provided in the Italian PatentApplication TO 99 A 000 802 which goes back to the same inventor,contemporaneously with the Italian Patent Application TO 99 A 000 803,the priority of which is claimed. In effect, the reduction of thetemperature peak, which is the object of this application, occurs alsounforeseeably with the employment of an automatic valve such as the onethat is the object of the first-mentioned Italian patent application.The insertion of a flow rate regulator in an automatic valve, accordingto said application, is therefore also an object of this invention forthe purpose of bringing about a reduction in the temperature peak thatoccurs during the period of transition involved in the regulation actionsubsequent to an abrupt variation in the water supply pressure of athermostatic mixing device.

Although the new use proposed by this invention relates especially tothe preferred application in a thermostatic mixing device for thepurpose of reducing its temperature peak during the regulationtransition period, a noteworthy advantage can be secured by acorresponding application in a nonthermostatic mixing device. This,naturally, does not give rise to a real temperature peak, but,corresponding to a variation in the pressure in one of the water supplypipes, it modifies the temperature of the mixed water that is drawnwithout in succession correcting this variation (as would a thermostaticmixing device). The use of one or two flow rate regulators, as describedin relation to a thermostatic mixing device, makes it possibleadvantageously to moderate the temperature variation of the water thatis drawn subsequent to a variation in the pressure in one of the watersupply pipes.

A new use of a flow rate regulating device is disclosed, whose featureconsists of the fact that, when inserted in a water pipeline, it permitsthe passage of a flow of water having a substantially constant flow rateand predetermined in keeping with the variation within certain limits ofthe pressure at which the water is supplied to the device, thusconstituting a variable resistance that is opposed to the water flow, ause designed especially to perform the function of reducing thetemperature peak presented by the mixed water drawn from a thermostaticmixing device during the transitory period of regulation when thepressure of the water supplied to one of the inlets of the thermostaticmixing device varies abruptly with respect to the pressure of the watersupplied to the other inlet of the thermostatic mixing device, said useconsisting of the insertion of said flow rate regulating device in thepassage of at least one of the flows of supply of cold water and hotwater directed to the thermostatic mixing device. The flow rateregulator can be inserted on the passage of both supply flows of coldand hot water, of the hot water supply flow only, or, and preferably, ofthe cold water supply flow only.

It must be understood that the invention is not confined to theembodiments described and illustrated by way of example. Severalmodifications are within the reach of the expert in the field, forexample, the installed flow rate regulator can be of a type differentfrom the one considered by way of example as long as it has similarfeatures; the thermostatic mixing device or even the nonthermostaticmixing device can be of a type that does or does not act as a faucet andcan be of any known type or of a special type involved in thermostaticmixing devices; if the flow rate regulator is installed in only one ofthe water supply connections, the other connection can be given a fixedchoking member or it can be devoid of such a member; if the presence ofa nonreturn valve is required, it can be installed in one or both of thewater supply pipes, regardless of whether it is incorporated in a flowrate regulator or whether it constitutes a member by itself.

These and other modifications and any substitution with technicalequivalents can be introduced in the subject matter described andillustrated above without departing from the scope and spirit of thepresent invention as defined by the appended claims.

What is claimed is:
 1. A hydraulic installation, comprising: athermostatic mixing device having an inlet connection (2) for receivinga flow of cold water through a cold water passageway, an inletconnection (3) for receiving a flow of hot water through a hot waterpassageway, and a delivery connection (4) for delivering mixed water;and a first flow rate regulating device (5) inserted in the cold waterpassageway, a second flow rate regulating device (6) inserted in the hotwater passageway, wherein the first flow rate regulating device offers agreater resistance to the water flow than the second flow regulatingdevice, and wherein the first flow rate regulating device (5) is adaptedto limit the passage of a flow of water to a predetermined andsubstantially constant flow rate, thus reducing the temperature peakpresented by the mixed water drawn from said mixing device when thepressure of the water supplied to one of said inlet connections (2, 3)varies abruptly with respect to the pressure of the water supplied tothe other inlet connection (3, 2).
 2. The hydraulic installationaccording to claim 1, wherein the first flow regulating device is of asimple type, devoid of any non-return means.
 3. The hydraulicinstallation according to claim 2, wherein the first flow rateregulating device (5) of the simple type is inserted in said inletconnection (2) for receiving the flow of supply of cold water.
 4. Thehydraulic installation according to claim 2, wherein the second flowregulating device is linked to a non-return means.
 5. The hydraulicinstallation according to claim 4, wherein the second flow rateregulating device (6) of the type linked to a non-return means (7) isinserted in said inlet connection (3) for receiving the flow of supplyof hot water.
 6. The hydraulic installation according to claim 1,further comprising means for restricting the pressure of the watersupplied to the first and second flow rate regulating devices to withina range from 1 to 10 bar of pressure.